Tom, in order to allow additional upstream mainline kernel developers to examine the issue, at your earliest convenience, could you please test the latest mainline kernel? Please keep in mind the following:
1) The one to test is in a folder at the very top of the page (not the daily folder).
2) The release names are irrelevant.
3) The folder time stamps aren't indicative of when the kernel actually was released upstream.
4) Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds .

If testing on your main install would be inconvenient, one may:
1) Install Ubuntu to a different partition and then test this there.
2) Backup, or clone the primary install.

If the latest kernel did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the mainline kernel, please comment on which kernel version specifically you tested. If this issue is not reproducible in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the Bug Description:
kernel-fixed-upstream
kernel-fixed-upstream-X.Y-rcZ

Where X, and Y are the first two numbers of the kernel version, and Z is the release candidate number if it exists.

If the issue is reproducible with the mainline kernel, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-X.Y-rcZ

Please note, an error to install the kernel does not fit the criteria of kernel-bug-exists-upstream.

Also, you don't need to apport-collect further unless specifically requested to do so.

In addition, to keep this issue relevant to upstream, please continue to test the latest mainline kernel as it becomes available.

Lastly, it is most helpful that after testing of the latest mainline kernel is complete, you mark this report Status Confirmed.

I can't replicate it since the report. I have no idea why, maybe the Ubuntu releases patched it. I haven't changed anything that should have fixed this, to my knowledge, but it just woke up again with wifi OK.

tom, this report is being closed due to your last comment https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1785319/comments/34 regarding this is no longer reproducible. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status. Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.